“…We evaluate explicitly the contributions of one- and two-instanton processes.…”
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“…However first calculations of instanton rate killed any hope to detect them even at very high energies while the calculation of sphaleron transitions rate is a tricky problem which continue being widely discussed. …”
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“…Explicit examples of topologically stable configurations carrying nonvanishing instanton number in four and eight dimensions are given, and they can be conjectured to exist in dimension $4k$. …”
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“…The type IIA result is then used to predict the full, non-perturbative correction to the heterotic effective action. We determine the instanton numbers and the Olive-Montonen duality groups.…”
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“…As a check of mirror symmetry we compute the structure of the space of complex structures of the mirror and check that this reproduces the known results for the Yukawa couplings and metric appropriate to the Kahler class parameters on the Z orbifold together with their instanton corrections.…”
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“…The phenomenon, T-dual to brane recombination in the intersecting-brane picture, shares some similarities to inverse small-instanton transitions in non-compact spaces, though in this case the Abelian magnetic background is a consequence of the compactness of the internal manifold, and is not ascribed to a zero-size non-Abelian instanton growing to maximal size. …”
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“…We also derive a nonlinear seventh order differential equation which directly governs the instanton corrected Yukawa coupling.…”
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“…We calculate gauge instanton corrections to a class of higher derivative string effective couplings introduced in [1]. …”
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“…We also discuss symmetries of the world-sheet instanton numbers in the type II theory, and interpret them in terms of S--duality of the non-perturbative heterotic string.…”
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“…We check heterotic/type II duality for one of the models by relating the modular forms in the heterotic description to the known instanton numbers in the type II description. We comment on the relation of our results to recent proposals for closely related models.…”
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“…We study the consistency of global 1-form symmetries corresponding to the center of the gauge groups, or subgroups thereof, by activating their background fields, which makes the instanton density fractional. In 6d, an instanton background for a given gauge theory sources BPS strings via tadpole cancelation. …”
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“…The current status of the problem of electroweak instanton-like processes at high energies is outlined. …”
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“…For one variable they reduce to linear fourth-order equations which are characterized by classical $W$-generators; we find that the instanton corrections to the Yukawa couplings are directly related to the non-vanishing of $w_4$. …”
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“…In addition to heterotic and type II constructions, we also realise the mass deformation in type I theory, thus leading to a natural way of uplifting the result to the instanton sector.…”
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“…We find that all three colliders are capable of providing meaningful information on the nature of instanton/sphaleron-induced processes at various energy scales.…”
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“…We re-examine the question of heterotic - heterotic string duality in six dimensions and argue that the E_8\times E_8 heterotic string, compactified on K3 with equal instanton numbers in the two E_8's, has a self-duality that inverts the coupling, dualizes the antisymmetric tensor, acts non-trivially on the hypermultiplets, and exchanges gauge fields that can be seen in perturbation theory with gauge fields of a non-perturbative origin. …”
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“…We connect the appearance of matter to the local geometry of the singularity and discuss the relation between the instanton numbers of the Calabi--Yau manifolds taking part in the transition. …”
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“…We find that one-loop gauge corrections of any orbifold limit of K3 with arbitrary choice of gauge bundles can always be expressed by their instanton numbers and generic automorphic forms. These functions classify also one--loop gauge thresholds of N=1 (0,2) heterotic compactifications based on toroidal orbifolds T^6/Z_N$. …”
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“…In this paper we show how this system reduces to one-dimensional motion on instanton moduli space. Quantization leads to the previous light-cone proposal of the (2,0) theory, generalized to include a potential that arises on the Coulomb branch as well as couplings to background gauge and self-dual two-form fields.…”
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“…Supersymmetry breaking is determined by QCD instanton effects, in an extremely minimal setup in which a single field drives the relaxation and breaks supersymmetry. …”
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